The invention relates to a tripod joint which includes three circumferentially distributed axis-parallel recesses forming circumferentially opposed tracks. The joint also includes an inner joint part with a star-shaped cross-section and three circumferentially distributed arms which engage the recesses of an outer joint part. The arms support roller assemblies, each including a roller carrier assembly and a roller, with the latter arranged on the arm to be longitudinally and angularly movable relative to the arm axis and pivotable relative to the arm axis.
The above definition covers a number of different prior art tripod joints. The solutions in accordance with the invention preferably refer to the first embodiment mentioned below, but analogously they are applicable to all three types of referred to embodiment.
In a first embodiment, each arm includes a part-spherical arm end on which a roller carrier with a cylindrical inner aperture is held so as to be axially movable relative to the arm axis and pivotable relative to the arm axis. A roller is rotatably held on each roller carrier, with preferably a needle bearing arranged between each roller carrier and roller.
In a second embodiment, each cylindrical arm includes an inner ring with an internally cylindrical surface which is guided so as to be axially movable relative to the arm axis. The inner ring includes a spherical outer face which engages an at least part-spherical inner face of a roller carrier which is held on the inner ring so as to be pivotable relative to the arm axis. A roller is rotatably held on each roller carrier, with preferably a needle bearing arranged between each roller carrier and roller.
Finally, in a third embodiment an internally cylindrical inner ring, with an outer spherical face, is rotatably held on each cylindrical arm. A roller, with an internally cylindrical face, is guided on the inner ring so as to be displaceable relative to the arm axis and pivotable relative to the arm axis. Preferably, a needle bearing is arranged between each arm and inner ring.
In the case of all embodiments mentioned, the roller assemblies, with their circumferentially undivided rollers, have to be slid radially on to the arm before it is possible for the inner joint parts with the slide-on roller assemblies to be introduced axially into the recesses in the outer joint part. For design reasons, the roller assemblies do not have a fixed position on the arms, to meet the required kinematic conditions, neither in the axial direction nor with reference to their angular position. This complicates manual assembly and does not permit an automatic assembly. In particular, when an inner joint part with slide-on roller assemblies and an outer joint part with horizontally positioned axes are to be inserted into one another, there is a risk of the roller assemblies pivoting on the tripod arms and thus they cannot be introduced into the recesses in the outer joint part, or they simply fall off the tripod arm as a result of their weight.